The present invention relates generally to the field of arc welding systems, and more particularly to an arc welding torch adapted to receive a cylindrical metal electrode.
TIG (Tungsten Inert Gas) welding (also known as gas tungsten arc welding, GTAW, or HELIARC) is a type of arc welding process in which an electric arc is maintained between a metal electrode and a metal object. The heat generated by the arc produces localized melting of the metal object. The electrode, typically tungsten, is secured to a torch to enable a user to direct the electrode and establish the point of contact between the electrode and the object. TIG welding may be performed with or without the addition of a filler metal. Typically, the weld puddle and the area surrounding the weld puddle are protected from the atmosphere by an inert gas. The inert gas prevents rapid oxidation of the weld and the surrounding metal.
The electricity for the welding process is provided by a power source through a welding cable coupled to the torch. Typically, the power source is a constant voltage AC, DC, or a combination AC/DC source. In addition, a TIG welding cable typically is adapted to transport the inert gas to the torch. Furthermore, the TIG welding process typically generates a substantial amount of heat in the electrode. Consequently, cooling fluid may be used to cool the torch. Thus, a welding cable for a TIG welding system may transport electricity, gas, and cooling fluid.
The metal electrodes used in TIG welding typically are shaped like long, cylindrical, metal rods. A TIG welding electrode is secured to a TIG welding torch by a collet, a backcap, and a collet body. To secure the electrode to the welding torch, the electrode is inserted through the collet and collet body. The collet body is threaded into a front portion of a threaded torch head disposed within the torch body. The backcap is threaded onto the rear portion of the torch head. As the backcap is threaded onto the torch body, the backcap drives the collet against the interior of the collet body. The collet is adapted to pinch down on the electrode as the collet is driven against an interior surface of the collet body, thereby securing the electrode to the torch. In addition, the collet body is adapted to enable gas to flow into the rear end of the collet body around the electrode and out through holes in the side of the collet body. A nozzle is used to direct the gas towards the object to be welded.
There are a number of problems associated with the use of conventional collets and collet bodies to secure an electrode to a welding torch. One problem is that the collet may be misaligned with the collet body during assembly. In addition, the welding electrode will become loose if the backcap is loosened because the surface used to hold the collet is tapered.
A need exists for a technique to enable an electrode to be installed in a welding torch more easily than with existing collets and collet bodies. More specifically, a need exists for a technique to secure an electrode to a welding torch without misalignment of the collet and collet body and to maintain the welding electrode secure even with movement of the collet relative to the collet body.